What a great idea for making permanent metal tags. I've bought them & they are pricey.
For any marking that has to hold up in full sun I use a black china marker that's oil based & seems to last years on any label: plastic, metal, wood or stone without fading like felt permanent markers. I have a white one to mark on dark things, too. The aluminum blind tags last years but plastic blinds get brittle after a year. I prefer to make some very durable plastic ones I recycle from the tall plastic drink cups from Taco Bell, Burger King & such. They are a good thickness that I just cut in my spare time into wedge shapes 1/2" to 1 1/2" wide at top x 4" long with a point. I have some 3 years old that are still pliable & readable tagging my day lilies in full sun & weather.
